Small flexible liquid core catheter for laser ablation in body lumens and methods for use

ABSTRACT

Embodiments relate to the design and use of a low profile ablation catheter with a liquid core for use in laser ablation removal of arterial plaque blockages to restore blood flow.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/651,070, filed Oct. 12, 2012, entitled Small Flexible LiquidCore Catheter for Laser Ablation in Body Lumens and Methods for Use, byJ. Laudenslager et al., which claims priority under 35 USC 119(e) fromU.S. Provisional Patent Application No. 61/547,435, filed Oct. 14, 2011,entitled Small Flexible Liquid Core Catheter for Laser Ablation andMethod for Use, by J. Laudenslager et al., the entirety of each of theaforementioned patent applications is incorporated by reference herein.

BACKGROUND

Laser catheters and laser delivery systems in general have wide range ofapplications in the medical field. Such systems may be used to deliverlaser energy to desired sites of a patient's anatomy, and may beparticularly suitable for delivering laser energy to locations within apatient's body that allow for minimally invasive treatment of a varietyof indications using a variety of treatment modalities. Examples of somelaser treatment modalities include heating tissue, stimulating tissue,drug activation within a patient's tissue and ablation of tissue.

Laser catheters currently approved for clearing blockages in humanarteries may use single or more commonly multiple bundle pure silicaoptical fibers for indications using ultraviolet laser pulse durationsgreater than about 50 nsec, usually greater than about 100 nsec toprevent damage to small diameter optical fibers used in multiple opticalfiber delivery catheter designs. Typically, optical fiber elementshaving a transmissive core with a transverse dimension or diameter ofabout 50 microns to about 100 microns may be used in ablation cathetershaving multiple optical fiber bundles.

In some cases, single large diameter optical fibers having atransmissive core with a transverse dimension or diameter greater thanabout 130 microns may be too stiff or resistant to longitudinal bendingfor use in the arteries of a patient, particularly the coronary arteriesof a human patient. Therefore, multiple optical fiber bundles usingoptical fibers having a smaller transverse dimension or diameter may beused to improve flexibility of the catheter while maintaining a constanttransmissive core area. These optical fiber laser catheters may be up to12 feet long and contain from about 50 optical fibers to about 300optical fibers depending on the cross sectional size of the catheterablation tip. These pure silica optical fibers are expensive and have alow percentage of cutting area due to the clad and buffer used on theoutside of the light conducting or transmissive core as well as a lowdensity packing factor for the multiple fibers having a circulartransverse cross section disposed in a bundle.

Another way for delivering laser energy to a remote site includes theuse of a fluid core waveguide. Existing commercial fluid core waveguideshaving a transmissive fluid core may typically have an inner diameter ofabout 2 mm to about 5 mm and a length of about 1 m to about 5 m and haveuseful light transmission from the ultraviolet to the visiblewavelengths at greater than 50% transmission in some cases. Such designsmay be robust for repeated use but are large in size and may not bescalable to a smaller more flexible design for use as a disposablecatheter in tortuous vessels such as a patient's vasculature. Suchdesigns may also not be adaptable to smaller more flexible embodimentsto be used with a high pulse power and high pulse energy laser such asthe ultraviolet excimer laser, particularly the 308 nm XeCl excimer.Also, many of the previously disclosed fluids used for the transmissivecore of these fluid core waveguides may not be suitably biocompatiblefor use inside the human body.

What has been needed is a fluid core waveguide based ablation catheterthat is small and flexible enough to navigate a patient's vasculature,uses biocompatible fluids, and is economical to manufacture. What hasalso been needed is a fluid core waveguide based ablation catheter thatcan be efficiently packaged and sterilized and maintain clinicalintegrity during a useful shelf life after shipment to an end user.

SUMMARY

Some embodiments of a laser catheter system to ablate blockages in bodylumens using high energy and high power short duration laser pulses mayinclude a high energy, high power short duration ultraviolet pulsedlaser source. Such systems may also include a low profile, kinkresistant, torqueable liquid core ablation catheter operatively coupledto the laser source. In some cases, the liquid core ablation cathetermay have an elongate multi-layer catheter tube including a thin innerluminal layer of a low index of refraction (IR), U.V. transparent,amorphous fluoropolymer having an index of refraction of less than orequal to about 1.33 disposed on an inside surface of the base tubularlayer; an ultraviolet grade output optical window or window assemblysealed to a distal end of the catheter tube; an ultraviolet grade inputoptical window sealed to a proximal end of the catheter tube to create afluid tight core liquid volume; and a biocompatible U.V. transparentfluid disposed within and completely filling the core liquid volumeformed between an inner surface of the thin inner luminal layer, theoutput optical window and the input optical window.

Some embodiments of a laser system to ablate blockages in body lumensusing high energy and high power short duration laser pulses include ahigh energy, high power short duration ultraviolet pulsed laser source.The system may also include a low profile, kink resistant, torqueableliquid core ablation catheter operatively coupled to the laser source.Such a liquid core ablation catheter may include an elongate multi-layercatheter tube, which has a base tubular layer including fluorinated ormostly fluorinated material, a braided layer disposed over an outsidesurface of the base tubular layer, an over-jacket layer coated over thebraided layer and base tubular layer to encapsulate the braided layer,and a thin inner luminal layer of a low index of refraction (IR), U.V.transparent, amorphous fluoropolymer having an index of refraction ofless than or equal to about 1.33 disposed on an inside surface of thebase tubular layer that may be made by drip coating a solution ofamorphous fluoropolymer to the inside surface and drying off thesolvent. The liquid core ablation catheter may also include anultraviolet grade output optical window sealed to a lumenal surface,such as an inner lumenal surface of the catheter tube, wherein an arearatio of the output optical window to a total area of an outer diameterof the catheter tube, and in particular, the catheter tube distal tip,may be greater than about 40%. The catheter may further include anultraviolet grade input optical window sealed to a surface of thecatheter tube, such as an inner lumenal surface or outer surface of thecatheter tube at a proximal end of the catheter tube to create a fluidtight core liquid volume. A biocompatible U.V. transparent fluid may bedisposed within and completely filling a core liquid volume formedbetween an inner surface of the thin inner luminal layer, a proximalsurface of the output optical window and a distal surface of the outputoptical window.

Some embodiments of a support catheter for use supporting a liquid coreablation catheter may include an inner tubular layer that may be lessthan about 0.001 inches in thickness, a thin over layer with of amaterial with a higher durometer than the inner tubular layer, a braidedlayer disposed over an outer surface of the inner tubular layer, and anouter layer covering the braided layer. In some cases, the supportcatheter may also have a wall thickness of less than about 0.006 inches.For some such embodiments, the support catheter may include an innerlumen with an inner diameter which is configured to accommodate passageof a liquid core ablation catheter and space therebetween sufficient forsaline injection to flush blood and contrast fluid in front of theablation catheter distal end. For some embodiments, the inner tubularlayer of this catheter may include a low friction material to easepassage of the ablation catheter and may also include the requisitetorqueability, pushability and kink resistance to guide an ablationcatheter with a low enough profile to advance through an openinggenerated by such laser ablation of tissue with the ablation catheter.Some support catheter embodiments may include a multi-lumen supportcatheter, having one or more guidewire lumens, such as 2, 3, 4 or moreguidewire lumens, and a working lumen configured for passage of anablation catheter.

Some methods of ablation of blockages in a lumen of a human vessel mayinclude positioning a support catheter at a target site of a blockage ofthe vessel, inserting a liquid core ablation catheter adjacent theblockage, injecting saline through an inner lumen of the supportcatheter to flush contrast fluid and blood from a distal tip of theliquid core ablation catheter, emitting ablative laser energy from adistal end of the ablation catheter and advancing the liquid coreablation catheter about 4 mm to about 6 mm from a distal end of thesupport catheter while lasing. In some cases, the ablation catheter maybe advanced about 5 mm from a distal end of the support catheter.Thereafter, the support catheter may be repositioned so as to besubstantially even with the ablation catheter and this process continueduntil the blockage is traversed.

Some other methods of making a multi-layer catheter tube for a liquidcore ablation catheter may use processes other than drip coating or dipcoating for generating a low index of refraction film or layer on aninside surface of the catheter tube. For example, some embodiments ofmaking a multi-layer catheter tube may include extruding a thin innerluminal layer of amorphous fluoropolymer onto a metal mandrel, etchingan outer surface of the extruded inner luminal layer, applying a baselayer tube configured as a water barrier over the etched outer surfaceof the inner luminal layer and applying a braided layer of thin metalfilaments onto an outer surface of the base layer tube with the metalmandrel in place. Thereafter, an outer jacket layer may be applied overan outer surface and braided layer and an outer surface of the baselayer tube and the metal mandrel removed from the inner luminal layer bystretching the metal mandrel to reduce an outer diameter thereof andwithdrawing the metal mandrel from an inner lumen of the inner luminallayer.

Some embodiments of a method of making an inner luminal layer of amulti-layer catheter tube of a liquid core ablation catheter may includecoating a metal mandrel with an over coat of an amorphous fluoropolymersolution and processing the coated mandrel at temperatures above aboiling point of a solvent of the amorphous fluoropolymer solution andabove a glass transition temperature (Tg) of an amorphous fluoropolymermaterial of the amorphous fluoropolymer solution to drive off thesolvent and anneal the amorphous fluoropolymer material and form aninner layer. Thereafter, the processed layer of amorphous fluoropolymermay be coated with one or more additional coats of amorphousfluoropolymer solution and the additional coat or coats processed attemperatures above the boiling point of the solvent of the fluoropolymersolution and above the glass transition temperature (Tg) of thefluoropolymer material of the fluoropolymer solution to drive off thesolvent and anneal the fluoropolymer material to form a multi-layerinner luminal layer of sufficient thickness. An outer surface of theinner luminal layer may then be etched with an appropriate etchingprocess to produce a bondable surface and a base layer tube configuredas a water barrier applied over the etched outer surface of the innerluminal layer. A braided layer of thin metal filaments may also beapplied onto the etched outer surface of the inner luminal layer withthe metal mandrel in place and an outer jacket layer applied over theetched outer surface and braided layer. Once the outer jacket has beenapplied, the metal mandrel may be removed from the inner luminal layerby stretching the metal mandrel to reduce an outer diameter thereof andwithdrawing the metal mandrel from an inner lumen of the inner luminallayer.

Some embodiments of a method of making a multi-layer catheter tube for aliquid core ablation catheter include applying a base layer tubeconfigured as a water barrier onto a metal mandrel, applying a braidedlayer of thin metal filaments onto an outer surface of the baser layertube with the metal mandrel in place and applying an outer jacket layerover an outer surface and braided layer and an outer surface of the baselayer tube. The method may also include removing the metal mandrel fromthe inner luminal layer by stretching the metal mandrel to reduce anouter diameter thereof and withdrawing the metal mandrel from an innerlumen of the inner luminal layer. The method may also include dripcoating a solution of amorphous fluoropolymer(s) onto an inside surfaceof the base layer and removing a solvent of the solution of amorphousfluoropolymer(s) to form an inner luminal layer of amorphousfluoropolymer(s).

Some embodiments of a laser catheter system to ablate blockages in bodylumens using high energy and high power short duration laser pulses,include a high energy, high power short duration ultraviolet pulsedlaser source and a low profile, kink resistant, torqueable liquid coreablation catheter operatively coupled to the laser source. The liquidcore ablation catheter may include an elongate multi-layer catheter tubeincluding a thin inner luminal layer of a low IR, U.V. transparent,amorphous fluoropolymer having an index of refraction of less than orequal to about 1.33 disposed on an inside surface of the base tubularlayer. The ablation catheter may also include an ultraviolet gradeoutput optical window or window assembly sealed to a distal end of thecatheter tube and an ultraviolet grade input optical window sealed to aproximal end of the catheter tube to create a fluid tight core liquidvolume. Further, a biocompatible U.V. transparent fluid may be disposedwithin and completely filling the core liquid volume formed between aninner surface of the thin inner luminal layer, the output optical windowand the input optical window.

Some embodiments of a high energy laser coupler have a coupler bodyincluding a proximal section with a cylindrical outer surface, an innerbore disposed concentrically within the cylindrical outer surface andextending distally from a proximal end of the coupler body, a windowconnector bore disposed at a distal end of the inner bore, and a distalsection extending distally from the window connector bore. Such lasercoupler embodiments may also have a window connector body including aproximal section with a cylindrical outer surface configured to fitclosely with an inside surface of the window connector bore of thecoupler body, a flange portion disposed at a distal end of the proximalsection, a stepped portion extending distally of the flange portion andan inner bore extending the length of the window connector body from aproximal end to a distal end thereof. An optical input window may bedisposed within and secured to the inner bore of the window connectorbody such that a proximal end of the optical input window extendsproximally from a proximal end of the proximal section of the windowconnector body. In addition, a flexible waveguide catheter tubeincluding a proximal portion thereof may be disposed over the steppedportion of the window connector body and a cylindrical metal sleeve maybe disposed over the proximal portion of the flexible waveguide cathetertube so at to secure the catheter tube to the stepped portion of thewindow connector body.

Some embodiments of a liquid core ablation catheter package assemblyinclude a thin walled hermetically sealed enclosure having an interiorvolume and a material suitable for gamma sterilization. The package alsoincludes a liquid core ablation catheter disposed within the interiorvolume of the hermetically sealed enclosure and a liquid disposed withinthe interior volume which is configured to maintain a vapor pressurewithin the interior volume sufficient to prevent loss of a liquid of aliquid core of the liquid core ablation catheter due to diffusion of theliquid core into the interior volume.

Some embodiments of an ablation catheter include an elongate catheterbody, a transmissive core which is configured to transmit high energylaser light and which extends longitudinally from a proximal end to adistal end of the elongate catheter body, and an input surface inoptical communication with the transmissive core at a proximal end ofthe elongate catheter body. The ablation catheter may also include anoutput surface in optical communication with the transmissive core at adistal end of the elongate catheter body. The ablation catheter may alsohave a tapered metal housing which includes a distal end having an innerbore that is disposed about the output surface, which includes a distalend that is longitudinally coextensive with a distal end of the outputsurface, which includes a tapered distal section that terminatesdistally with a thin wall that facilitates passage of a distal end ofthe ablation catheter through a lumen within a patient's body and whichis configured to be sufficiently radiopaque in such as to be viewable byfluoroscopic imaging during a medical procedure.

Certain embodiments are described further in the following description,examples, claims and drawings. These features of embodiments will becomemore apparent from the following detailed description when taken inconjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments of the technology and are notlimiting. For clarity and ease of illustration, the drawings may not bemade to scale and, in some instances, various aspects may be shownexaggerated or enlarged to facilitate an understanding of particularembodiments.

FIG. 1 is a perspective view of a laser system embodiment including alaser and a disposable liquid core ablation catheter coupled to thelaser.

FIG. 2 is a perspective view of a laser system embodiment including areusable extension waveguide connected between a laser and a disposableliquid core ablation catheter.

FIG. 3 is an elevation view of an embodiment of a laser catheter systemincluding a liquid core ablation catheter disposed within a supportcatheter, the support catheter having a saline flush port.

FIG. 4 is an elevation view of the support catheter embodiment of FIG.2.

FIG. 5 is an elevation view of the liquid core ablation catheterembodiment of FIG. 2.

FIG. 6 is an enlarged elevation view in partial section of the laserconnector ferrule embodiment of FIG. 3 for use with a liquid coreablation catheter.

FIG. 7 is an enlarged view of the encircled portion 7 of the laserconnector ferrule embodiment of FIG. 6.

FIG. 8 is an elevation view in partial section of a distal portion ofthe liquid core ablation catheter embodiment of FIG. 3.

FIG. 9 is a transverse cross sectional view of the liquid core ablationcatheter of FIG. 8 taken along lines 9-9 of FIG. 8.

FIG. 10 is an elevation view in section of a distal portion of a liquidcore ablation catheter embodiment including a tapered metal housing.

FIG. 11 is a transverse cross sectional view of the liquid core ablationcatheter of FIG. 10 taken along lines 10-10 of FIG. 10.

FIG. 12 is a transverse cross sectional view of the liquid core ablationcatheter of FIG. 10 taken along lines 12-12 of FIG. 10.

FIG. 13 is a transverse cross section of the liquid core ablationcatheter embodiment of FIG. 5 taken along lines 13-13 of FIG. 5.

FIG. 14 is an enlarged view in section of the wall of the liquid coreablation catheter of FIG. 13 indicated by the encircled portion 14 inFIG. 13.

FIG. 15 is a transverse cross section view of an embodiment of a liquidcore ablation catheter with an eccentric guidewire lumen.

FIG. 16 is an elevation view of a distal portion of the liquid coreablation catheter embodiment of FIG. 15.

FIG. 17 is an elevation view of a distal portion of an embodiment of theliquid core ablation catheter embodiment of FIG. 15 having a taperedmetal housing disposed at a distal end thereof.

FIG. 18 is a transverse cross section view showing an embodiment of thesupport catheter of FIG. 4 and taken along lines 18-18 of FIG. 4.

FIG. 19 is an elevation view of a distal portion of the support catheterembodiment of FIG. 18.

FIG. 20 is an elevation view of a distal portion of a support catheterembodiment that includes a tapered distal portion.

FIG. 21 is an elevation view of a distal portion of a support catheterembodiment that includes an angled distal end.

FIG. 22 is an elevation view of a distal portion of a support catheterembodiment having an angled distal section configured for nutation of anablation catheter disposed therein.

FIG. 23 is an end view of the support catheter of FIG. 22.

FIG. 24 is a schematic representation of an annular area of ablationswept by the distal end of the liquid core ablation catheter whileundergoing nutation due to rotation of the angled support catheter ofFIG. 22.

FIG. 25 is a schematic representation of a circular area of ablationswept by the distal end of the liquid core ablation catheter whileundergoing nutation due to rotation of the angled support catheter ofFIG. 22.

FIG. 26 is a perspective view of a distal portion of an embodiment of amulti-lumen support catheter having two eccentric guidewire lumens.

FIG. 27 is an end view of the support catheter embodiment of FIG. 8A.

FIGS. 28 through 32 illustrate a method embodiment of a tissue ablationmethod.

FIG. 33 is a transverse section view of a patient's vessel illustratinga method embodiment of producing a larger lumen after a first pass of anablation catheter.

FIG. 34 is an elevation view in partial section of a patient's vessellumen and catheter system embodiment disposed therein.

FIG. 35 is an elevation view in partial section illustrating an ablationcatheter ablating new tissue laterally adjacent the pilot lumen.

FIG. 36 is an elevation view in partial section illustrating creation ofan annular area of ablation of a vessel blockage by nutation of anablation catheter as shown in FIGS. 22-24.

FIGS. 37-43 illustrate schematic representations of various cathetermanufacturing process embodiments.

FIG. 44 is an elevation view in section of a distal portion of a liquidcore ablation catheter embodiment including a tapered metal housing.

FIG. 45 is a transverse cross section view of the liquid core ablationcatheter of FIG. 44 taken along lines 45-45 of FIG. 44.

FIG. 46 is an enlarged elevation view in partial section of a laserconnector ferrule embodiment of FIG. 3 for use with a liquid coreablation catheter.

FIG. 47 is a transverse cross section view of the laser coupler of FIG.46 taken along lines 47-47 of FIG. 46.

FIG. 48 is a transverse cross section view of the laser coupler of FIG.46 taken along lines 48-48 of FIG. 46.

FIG. 49 is an enlarged view of the encircled portion 49 of the laserconnector ferrule embodiment of FIG. 46.

FIG. 50 is a transverse cross section view of the input optic couplerassembly of the laser coupler of FIG. 49 taken along lines 50-50 of FIG.49.

FIG. 51 shows a schematic representation of a packaging embodiment foruse with a liquid core ablation catheter.

DETAILED DESCRIPTION

As discussed above, laser catheters and laser delivery systems ingeneral have wide range of applications in the medical field. Suchsystems may be used to deliver laser energy to desired sites of apatient's anatomy, and may be particularly suitable for delivering laserenergy to locations within a patient's body that allow for minimallyinvasive treatment of a variety of indications using a variety oftreatment modalities. Examples of some laser treatment modalitiesinclude heating tissue, stimulating tissue, drug activation within apatient's tissue and ablation of tissue. Some examples of clinicalindications for laser treatment may include laser atherectomy. Onedrawback of some current laser systems is the cost of the systems anddevices used to deliver the laser energy, particularly with regard tothose components that are designated as single use products. Liquid corecatheter embodiments 22, as shown in FIG. 3, may generally beconsiderably less expensive than a silica fiber optic based catheter andmay also have less dead space in the cutting area at the distal end ofthe catheter. The reduced dead space (that distal surface area that isnot emitting laser energy) may be an important feature for ablation ofblockages in arteries and for the ability of the catheter to cross alesion in a patient's vessel.

FIGS. 1-27 show a laser ablation system embodiment 8 that includes alaser energy source 10 including a housing 12, a power cord 14, anactivation footswitch 16, a control panel 18 and an output coupler 20. Aliquid core ablation catheter 22 has a laser coupler 24 which isdisposed at a proximal end 30 of the ablation catheter 22 and which iscoupled to the output coupler 20 of the laser source 10. The ablationcatheter 22 is disposed within an inner lumen 28 (as shown in FIG. 18)of a support catheter 26 which may be used to guide or support theablation catheter 22 within a body lumen of a patient. The supportcatheter 26 includes a Y-adapter 32 coupled to a proximal end 30thereof. The liquid core ablation catheter 22 is disposed within andpasses through a central lumen (not shown) of the Y-adapter 32 as well.The support catheter 26 and ablation catheter 22 each may have aradiopaque marker 31 disposed at a respective distal end thereof. Aworking length of the liquid core ablation catheter 22 may include thelength inside the patient's body between the access point and the targetlesion site and the length outside the body necessary to couple or passthrough the Y connector 32. An additional length may be needed to couplethis working distance of about 90 cm to about 120 cm to the laser source10 in some cases. If a laser source is large and located away from thepatient, an additional length of waveguide may be necessary. Some lasercatheter embodiments may be about 2 meters to about 3 meters long insome cases. In some cases, the laser source 10 of the laser system 8 mayinclude a XeCl excimer laser which produces high energy pulses at awavelength of about 308 nanometers, however, other high energy pulsedultraviolet laser sources may be used. Some laser source embodiments 10may have a pulse width of less than about 50 nanosec and a repetitionrate of up to about 100 Hz. Some such laser source embodiments 10 may becapable of producing about 20 to about 100 mJ/pulse.

For some embodiments, the laser system 8 may also include an aimingdiode (not shown) for applications where locating the distal tip 34 ofliquid core ablation catheter 22 visually may be desirable. For someembodiments, a red color diode light source (not shown) may be used.This red diode wavelength may have a wavelength that is configured topenetrate some tissue types and may provide visibility of the distal tip34 of the liquid core ablation catheter 22 and its position in the leganatomy. The red diode light source may be located in the laser coupler20 of the laser source 10 and coupled to the liquid core ablationcatheter 22 by turning mirror or beam splitter (not shown) in somecases.

Since some ablation catheters 22 are generally disposable or single useonly, the long 2-3 meter working length may be costly. For embodimentsdiscussed herein, a robust liquid filled extension waveguide 36 forcoupling from the laser source 10 to the single use disposable liquidcore ablation catheter 22 may be used outside a patient's body and bedesigned to last for multiple uses. Such an optional extension waveguide36, as shown in FIG. 2, may be used to connect the laser source 10 ofthe laser system 8′ to a single-use liquid core ablation catheter 22 andhave a length suitable to reach from the laser source 10 to the patienttable (not shown). In some cases, the extension waveguide 36 may have alength of about 75 cm to about 300 cm, more specifically, about 75 cm toabout 150 cm. The extension waveguide 36 may also be configured tocontain a higher IR liquid core fluid than disposable liquid coreablation catheter embodiments 22 because it is generally disposed andused outside the patient's body and is not subject to some of the samedesign constraints as discussed above. As such, core liquids that have ahigher IR may be used that may not be biocompatible in some cases.

With regard to laser system embodiments 8 such as those shown generallyin FIGS. 1 and 2, there are some features of the ablation cathetersystem 27, which includes the liquid core ablation catheter 22 andsupport catheter 26, shown in more detail in FIG. 3, that may bedesirable or even necessary in some cases to function as desired. Theliquid core ablation catheter 22, as shown in more detail in FIGS. 3, 5,6, 8 and 10, includes a multi-layer catheter tube 38 having a lowprofile to fit inside particular blood vessels, which may have innerluminal diameters or inner transverse dimensions that vary in size fromabout 2 mm to about 6 mm. The wall thickness of the multi-layer cathetertube 38 of the liquid core ablation catheter 22 may be thin relative toa transverse dimension of the liquid core 40, as shown in FIG. 13, toinsure flexibility and to minimize the “dead space” between an outerdistal surface 42 of the output window 82 (shown in FIG. 8) which emitstissue ablating energy and an outer dimension of the multi-layercatheter tube 38 which does not emit tissue ablating energy. Thenon-emitting wall of the catheter tube 38 forms the “dead space” thatdoes not contribute to tissue cutting or ablation. As such, the ablationcatheter 22 has a large fraction of cutting area relative to the overallarea of the distal tip or surface of the ablation catheter. This may beachieved by having a multi-layer catheter tube 38 with a thin wallthickness as shown in FIG. 13.

For some embodiments, the multi-layer catheter tube 38 of the ablationcatheter 22 is flexible enough to maneuver around bends in a patient'sartery without kinking yet be stiff enough to be able to push theablation catheter 22 through the vessel while ablating blockages. Insome cases, the catheter tube 38 is able to be torqued and rotated atthe distal end of the catheter tube 38 from a proximal portion 39 of thecatheter tube 38 that extends outside the patient's body.

In some cases, the core fluid 40 used in the ablation catheter 22 istransparent in the ultraviolet laser energy wavelengths and may be abiocompatible fluid in case of accidental leakage from the catheter 22.In addition, the configuration of fluid core ablation catheter 22 may becapable of transmitting high power pulses above a tissue ablationthreshold in the ultraviolet wavelength range preferably with pulsewidths shorter than 50 nsec and at repetitions rates of up to 100 Hz inorder to achieve the desired results in some cases. For someindications, the liquid core ablation catheter 22 may be designed forsingle use only but may also have a long shelf life after sterilizationof typically one year or more for use in a clinical setting. Therefore,the core liquid 40 disposed in the inner lumen 46 of the ablationcatheter 22 should not diffuse out of the thin wall multi-layer cathetertube 38 of the catheter system 27, as shown in FIG. 3, over this type oftime period for some embodiments. Also, for some embodiments, thematerials of the multi-layer catheter tube 38 may be sterilizablewithout significant degradation or degradation that would render theablation catheter 22 unusable. Gamma or X-ray sterilization may be idealin some situations and may be useful in order to ensure that any fluid,such as liquid water used for a transmissive core, inside the ablationcatheter is sterilized.

For some embodiments, the transmission of laser energy through theliquid core ablation catheter 22 is high enough to enable a relativelysmall laser source to be used for the laser system 8 in order to savecost. For some indications, the ablation catheter 22 allows sufficienttransmission to achieve a minimum output energy per pulse to ablatediffering arterial plaque types. In some cases, such a minimum outputenergy may range from about 4 milli-Joules/mm² (mJ/mm²) to about 14mJ/mm² for a XeCl laser at a wavelength of about 308 nanometers (nm) andan approximate pulse width of about 10 nanoseconds (nsec) in some cases.Longer 308 nm laser pulses of about 100 nsec may have slightly higherablation thresholds for the same tissue types. As such, a fluid for thecore of the liquid filled waveguide may transmit high power and highpulse energy ultraviolet excimer laser pulses in some cases and may bebiocompatible for insertion into human arteries. Pure water and normalsaline (0.9% NaCl aqueous solution) are highly transparent and arebiocompatible but they both have very low indices of refraction (IR)compared to the IR of most polymer tubing materials used in liquidwaveguide catheters. For example, at a temperature of about 20 degreesC., water has an IR of about 1.333 in the visible wavelength region andnormal saline has an IR of about 1.335. Teflon® fluorinated ethylenepropylene (FEP) tubing may have an IR in the visible range of light ofabout 1.338 which may be too high to produce an effective waveguideusing water or saline for some ablation catheter embodiments 22. This isbecause the IR of the inner luminal layer 48 of the catheter tube 38 asshown in FIG. 14, must be less than the IR of the fluid core 40 toachieve total internal refraction of laser energy being guided by theliquid core ablation catheter.

Embodiments of the catheter system 27 may be used for navigation withinthe tortuous anatomy of a patient's vasculature may include a multilayerdesign or designs. In some cases, a central catheter tubing core 50 maybe braided with a metal wire or ribbon 52 and this portion may have anover jacket 54 as shown in FIG. 13. This type of design may be used forapplications that require high torque, burst pressure resistance,pushability, steerability and kink resistance. The physicalcharacteristics of such a braided catheter embodiment 27, as shown inFIG. 3, may be varied by using different durometer values for theplastic tubing of the catheter body and by varying the pitch andthickness for the metal braid. This basic design concept may be appliedto the unique characteristics of liquid core ablation catheterembodiments 22.

In some cases, the laser ablation catheter system 27 includes means ofguidance of the ablation catheter through a vessel lumen or blockagethereof, such as an arterial blockage. Guidewire 56, as shown in FIG.31, which is disposed in a concentric or eccentric position within avessel 119 may be used in some cases and may pass through one or moreguidewire lumens, such as guidewire lumen 58 of the liquid core ablationcatheter embodiment 22′ as shown in the embodiments of FIGS. 15 and 16.The ablation catheter 22′ includes an eccentric guidewire lumen 58disposed along an outer surface of the ablation catheter 22. Theguidewire lumen may have a distal port disposed proximally from a distalend of the ablation catheter 22′ by at least about 5 mm. The guidewirelumen 58 may have a longitudinal length of at least about 10 cm. Supportcatheter embodiments 26′″ including one or more guidewire lumens such asthe two guidewire lumens 60 and 62, as shown in the embodiments of FIGS.26 and 27, may also be used to guide and support the ablation catheter.

In addition, straight support catheters 26 as shown in FIG. 19 or angledsupport catheters 26′ as shown in FIG. 21, may be used for guiding aliquid core ablation catheter 22 through restenosed stents in that thestent itself may serve as a guide to prevent the ablation catheter 22from causing an arterial wall perforation. Some support catheterembodiments may include a tapered support catheter embodiment 26″,angled support catheter embodiment 26′ or profiled support catheterembodiment as shown in FIGS. 20 and 21 to help center the liquidwaveguide ablation catheter 22 remain in the vessel lumen 118 during useas shown for example in FIGS. 28-32. The angled support catheterembodiment 26′ as shown in FIG. 21, may have an angled distal tip with adischarge axis 57 disposed at an angle, indicated by arrow 59, withrespect to a nominal longitudinal axis 61 of the support catheter 26′.For some embodiments, the angle 59 of the discharge axis of the supportcatheter 26′ may be about 5 degrees to about 45 degrees, morespecifically, about 10 degrees to about 30 degrees.

In addition, an angled support catheter embodiment 26′, as shown inFIGS. 22-25, may be rotated about its longitudinal axis, as shown byarrow 65 in FIG. 22, over an ablation catheter, such as liquid coreablation catheter 22, which extends distally therefrom. Such rotation ofan angled support catheter 26′ with a deflected distal section mayresult in orbiting or nutation of the distal tip of ablation catheter 22during the ablation process, i.e. during emission of ablation energysuitable for tissue ablation from the distal end of the liquid coreablation catheter 22. This nutation of the ablation energy emittingsurface of the liquid core ablation catheter 22 may produce a band orannulus of ablation or tissue removal as shown in FIG. 24. Such aprocess is also illustrated in the elevation view of a tissue ablationprocess shown in FIG. 36. The band or annulus of ablation produced bysuch and configuration and method may be suitable to create a largerneo-lumen or passage through a lumenal obstruction or constriction thanwould be possible by pushing the same liquid core ablation catheter 22directly through the obstruction or constriction in a straight line.Although FIGS. 24 and 36 illustrate a band or annulus of ablationcarried out by nutation of the support catheter 26′ about the liquidcore ablation catheter 22, a circular area of ablation may also begenerated for rotations with lesser nutation magnitudes as shown in FIG.25. In such cases, some portion or portions of the emitting surface ofthe distal end of the liquid core ablation catheter 22 would be disposedover a center of the neo-lumen being ablated into the obstructivetissue. In such cases, the neo-lumen may still be substantially largerthan an outer surface of the emitting surface or outer transversedimension of the liquid core ablation catheter 22. In some instances,the angled distal section of the angled support catheter 26′ may have alength, as shown by arrow 63 in FIG. 22, of about 5 mm to about 50 mm,more specifically, about 5 mm to about 15 mm. In some cases, a dischargeangle as indicated by arrow 59′ in FIG. 22 may be about 3 degrees toabout 10 degrees.

In some cases, the numerical aperture of a liquid core ablation catheter22 may be above a certain minimum value in order to prevent losses inthe catheter, particularly due to bending of the catheter. The numericalaperture of the liquid core ablation catheter 22 depends to a largeextent on the difference between the IR of the core liquid 40 and the IRof an inner luminal layer 48 of the multi-layer catheter tube 38. Theinner luminal layer 48 is a tubular layer of material or materials ofthe catheter tube 38 which surrounds the core liquid 40 within theliquid core ablation catheter 22. The inner luminal surface 64 (shown inFIG. 14) of the inner luminal layer 48 is the surface that contacts thecore liquid 40. It is the interface between the core liquid 40 and theinner luminal layer 48 that may be configured to generate total internalrefraction of laser light disposed and propagating within the coreliquid 40. As such, in some cases, the IR of the core liquid 40 shouldbe greater than an IR of the inner luminal layer 48 of the catheter tube38 by at least about 0.02.

The inner luminal layer 48 of the catheter tube 38 may also betransparent or substantially transparent to the wavelength of laserenergy being transmitted through the core liquid 40. This may beparticularly desirable because the U.V. radiation refracting at the coreliquid 40 inner luminal layer 48 interface may extend into the innerluminal layer 48 (and possibly beyond the inner luminal layer 48 of themulti-layer catheter tube 38) by a distance of about several wavelengthsduring the refraction process. When the refracted light extends into theinner luminal layer 48 (or any other subsequent layers of themulti-layer catheter tube 38 such as the base layer tube 50 as shown inFIG. 14) during the refraction process it may be strongly absorbed ifthe material of the inner luminal layer 48 is not transparent orsubstantially transparent to the wavelength and energy density of therefracted light. This means that many materials may be incompatible foruse as an inner luminal layer 48 of the multi-layer catheter tube 38 ofthe liquid core ablation catheter 22, particularly for embodiments usinga core liquid 40 of water or normal saline.

In view of the foregoing, inner luminal layer embodiments 48 may begenerated by coating an internal surface 66 of the base layer 50, asshown in FIG. 14, of a multi-layer catheter tube 38 made from commoncatheter materials with a film of material having an IR of less thanabout 1.33. As discussed above, it may be important for such a coatingmaterial to be transparent or substantially transparent to theultraviolet wavelength used in the corresponding catheter. In addition,the inner luminal layer 48 may also have a sufficient wall thickness toretain the high power U.V. laser energy and prevent substantial lossesthrough the inner luminal layer 48 to those layers of the catheter tube38 surrounding the inner luminal layer 48 as for some embodiments, thesurrounding tubular layers may include materials which absorb the U.V.laser energy and may be damaged or destroyed by it.

Certain amorphous fluoropolymers may be used as coatings having a low IRrelative to some core liquids 40 and thus may be used for the generationof an inner luminal layer 48 of catheter tubes 38. DuPont® Corporationlocated in Wilmington Del. has developed certain coatings including, inparticular, fluorinated (ethylenic-cyclo oxyaliphatic substitutedethylenic) copolymer (Teflon AF®) which is a family of amorphousfluoropolymers based on copolymers of2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole (PDD) andtetrafluoroethylene (TFE). According to DuPont, the principledifferences between the various grades of Teflon AF® are based solely onthe relative amounts of TFE to PDD in the polymer chain. Teflon AF®polymers have the lowest index of refraction of any known polymer andare substantially transparent to light, even at U.V. wavelengths makingthese materials suitable as low index coatings for waveguideapplications. In some cases, these amorphous fluoropolymers may beformulated with different IRs. Teflon AF 2400® has a TFE to PDD ratio ofabout 11:89 and a particularly low IR of about 1.29 in the visible lightwavelength range. Teflon AF 1601® has a TFE to PDD ratio of about 36:65and an IR of about 1.31 at the visible light wavelength range. Either ofthese formulations may be used to form an inner luminal layer 48 of themulti-layer catheter tube 38 of the ablation catheter 22. It should benoted that the IR of these fluorinated polymers as well as the IR ofwater and normal saline, increase in value for UV wavelengths relativeto values for light in the visible wavelength range.

We have measured the transmission of 308 nm laser pulses through bothwater and saline filled tubes of uncoated Teflon® FEP and observed thatthe light was lost in the first foot of the tube. Pulses having awavelength of about 308 nm may be readily transmitted through a meterlong FEP tube filled with the same fluids when the tube was lined withTeflon AF 1601®. Therefore, in the UV the IR difference between water orsaline and the Teflon AF 1601® or Teflon AF 2400® appears to besufficient for total internal refraction and high transmission of shortpulse laser energy having a pulse width of less than about 50 nsec and awavelength of about 308 nm.

These amorphous fluoropolymers discussed above may be soluble inselected solvents to facilitate coating processes. In some cases, theseamorphous fluoropolymer coatings adhere best to fluorocarbon polymersbut not very well to other plastic types. As such, when using anamorphous fluorinated polymer material for an inner luminal layer 48 ofthe embodiments herein, the choice of suitable materials for theremaining layers of the catheter tube 38 may be limited. These and otherproperties of the amorphous fluorinated polymer materials may alsocreate difficulties for construction of suitable catheter tubes 38utilizing amorphous fluorinated polymer materials for the inner luminallayer. For example, Teflon AF 2400® which has an IR of about 1.29 isgenerally produced in a 1% solution which may be too dilute to achieve asufficient coating thickness to confine U.V. laser energy to the coreliquid 40 and inner luminal layer 48. Teflon AF 1601® withconcentrations up to about 18% may be used to produce a coating for aninner luminal layer 48 with sufficient thickness to confine U.V. laserenergy at 308 nm wavelength and with an IR of about 1.31.

Teflon® FEP tubes may not be as suited for use with liquid filled laserwaveguides 22 because water and aqueous solutions of saline over timewill diffuse out of the FEP tube in low humidity environments. As anexample, we filled a thick wall tube of Teflon® FEP with water, sealedthe ends and placed it in an oven at 50 degrees C. and saw bubbleformation within 10 days. In some cases, we might prevent this diffusionof water by placing the FEP water filled tube in a plastic enclosurewhich contains water. In some cases, catheters 22 may be placed in anoven at about 50 degrees C. to about 60 degrees C. for several months toperform accelerated lifetime testing to simulate a one year shelf life.Therefore, the multi-layer catheter tube 38 of the ablation catheter 22must not have a high permeability for water transfer at oventemperatures of about 50 degrees C. to about 60 degrees C. to qualify asa medical catheter for long shelf life in some cases. In addition, forsome applications, the tubing material or materials of the multi-layercatheter tube 38 and/or support catheter 26 should be able to besterilized with gamma radiation or x-rays. Teflon® FEP is generally notas suitable for radiation sterilization.

Another disadvantage with using an FEP tube liner may be that thehardness shore durometer of about 55 D is about half that of PCTFE whichmay have a shore hardness of about 85 D to about 95 D. When the FEPliner is thin and has a low durometer then there may be an impression ofthin elements of a braid material 52 used on an outside surface 68(shown in FIG. 14) of a base tube 50 of the multi-layer catheter tube 38to transfer into the inner luminal surface 64 of the inner luminal layer48 which may cause the light to be scattered out of the tube. Also, whenan ablation catheter 22 is placed in the Y adapter 32 and acorresponding hemostatic valve thereof, the valve may compresses a lowdurometer ablation catheter embodiment 22, distort the wall structure ofthe ablation catheter and hinder transmission of light therethrough.

We have found that polychlorotrifluoroethylene, PCTFE, has one of thelowest diffusion rates for water compared to other polymer plastics, andcan be coated with Teflon AF® solutions and can also be sterilized usingradiation. We filled a thin wall PCTFE tube with water and sealed theends of the tube and placed the sealed assembly in an oven at 60 degreesC. for one month. No diffusion of the water in the PCTFE tube wasapparent even after the one month dwell time in the oven. As such, PCTFEmay be used in some cases for certain layers of the multi-layer cathetertube 38.

The higher durometer for PCTFE of about 90 D even with thin walls ofabout 0.002″ may provides extra stiffness that resists penetration ortransfer of a braid pattern onto an inner luminal surface 64 of theinner luminal layer 48 a liquid core ablation catheter 22. This higherdurometer may also add stiffness and pushability to the multi-layercatheter tube 38, but might kink easily in some cases without the metalbraid 52. PCTFE tubing does have a draw back in that the maximum workingtemperature of the material may be about 125 degrees C. in some cases.For some embodiments, the ablation catheter 22 may include a multi-layercatheter tube 38 an outer layer or over-jacket 54, as shown in FIGS. 13and 15, having a lower hardness durometer of about 65 D to about 75 D,more specifically, about 70 D. In some cases, the outer layer orover-jacket layer 54, as shown in FIG. 13, may have to be processed at atemperature level where the PCTFE wall of the base tube is notcompromised. This may have the effect of substantially limiting thechoice of materials and processing methods for the over-jacket 54 forthe multi-layer catheter tube 38 of the liquid core ablation catheter22.

There are several options for forming the inner luminal layer 48 of themulti-layer catheter tube 38 from an amorphous Teflon AF® or othersuitable amorphous fluoropolymer on the inside of a base tube 50, suchas a PCTFE or FEP base tube 50. One method of creating such an innerluminal layer 48 includes using a solution of Teflon AF® dissolved atpercentages of about 1% to about 18% Teflon AF® solids in a suitablesolvent such as Fluorinert solvent. One type of Fluorinert is aperfluorcarbon made by 3M Company under the description FC-40. TheFluorinert solvent may be offered in various formulations that havediffering boiling points. In some cases, a Fluorinert solvent having aboiling point of about 155 degrees C. may be used for the processesdiscussed herein.

One or more coatings may be applied to the inside of the PCTFE tube andthe solvent may then be evaporated off to leave a thin layer solid filmof low IR of Teflon AF® of about 5 microns to about 50 microns thick,more specifically, about 5 microns to about 20 microns thick. VariousTeflon AF® layers with differing IRs and concentrations may be appliedor mixtures of differing solutions may be applied in a single mixedlayer. Examples of amorphous coatings with low indices of refraction mayinclude Teflon AF 1601®, Teflon AF 2400®, Cytop® manufactured by AsahiGlass Company located in Japan, and Hyflon AD 40® or Hyflon AD 60® madeby Solvay Solexis Company located in Italy. Any of these amorphousfluoropolymers may be mixed with a high boiling point perfluoropolyether(PFPE) oil to provide thicker layers at lower cost. In some cases, aPFPE oil such as Fomblin YR 1800® sold by the Solvay Solexis Company maybe used. The boiling point of such a PFPE oil may be about 220 degreesC. to about 275 degrees C. for some embodiments.

Regarding the processing of some inner luminal layer embodiments 48, themanufacturer recommends in some cases that these amorphous fluoropolymercoatings be annealed above the boiling point of the solvent used andthen tempered for several minutes above the glass transitiontemperature, Tg, of the solid amorphous fluoropolymer film which may beabout 160 degrees C. for Teflon AF 1601® and about 240 degrees C. forTeflon AF 2400®. Exposure to these temperatures might be detrimental forthe PCTFE tube and other low melt plastics such as Pebax® used for theover-jacket 54 on the metal braid 52 of the multi-layer catheter tube 38of the liquid core ablation catheter 22. In some embodiments, Pebax®materials may have a melting temperature of about 135 degrees C., whichis well below the recommended processing temperatures to both remove thesolvents and get the materials above the Tg of the amorphousfluoropolymer. Method embodiments discussed herein were specificallydeveloped to enable the application of these films onto an inner luminalsurface of a PCTFE tube (or the like) to create the inner luminal layer48 of the ablation catheter 22. In some cases, these techniques userelatively lower process temperatures for longer time durations toachieve workable amorphous fluoropolymer inner luminal layers 48, asshown in FIG. 14, for multi-layer catheter tubes 22 which may then befilled with a liquid core 40 such as water or saline.

For some embodiments, a method of generating a multi-layer catheter tube38 may include a drip coating method whereby a solution of amorphousfluoropolymer or mixtures thereof are dissolved in solution such asFluorinert FC-40® from 3M at concentrations high enough to provide atleast a 5 micron or more layer thickness per coat. One or moremulti-layer catheter tubes 38 may be mounted vertically and cleaned onthe inside luminal surface with isopropyl alcohol or the like. The innerluminal surface of the catheter tube 38 may then be coated with thesolution of amorphous fluoropolymer for a given dwell time and annealedat temperatures less than about 100° C. or the melting point of themultilayer catheter material for times sufficient to remove all thesolvent. In some cases, dwell time at temperatures of less than about100° C. may be up to about 4 hours. The lower temperatures for annealingmay be configured or otherwise selected in order to prevent thermaldamage to the polymer materials of the multi-layer catheter tube 38 towhich the coating is being applied. This drip coating process may berepeated multiple times to produce an inner luminal layer 48 thicknessand uniformity that encapsulates or otherwise contains high power laserenergy at a wavelength of about 308 nm in the resulting waveguide coreof an ablation catheter 22 constructed from such a multi-layer cathetertube 38 and core-inner luminal layer junction therein. After processing,the multi-layer catheter tube 38 may be filled with an appropriate coreliquid 40 and sealed with suitable windows at both proximal and distalends thereof.

For some embodiments, the inner luminal layer 48 should also be thickenough to smooth out any surface irregularities on the inner surface ofa drip coated tube, such as a base layer tube 50 made from PCTFE, FEP orthe like. For some embodiments, a thickness of about 5 microns to about15 microns for the low IR internal material of the inner luminal layer48 might provide for an efficient coating. In some cases, Teflon® FEP orother fluoropolymer based materials may be used as an alternative toPTCFE for making base layer tubes 50 (see FIG. 14), however, there maybe issues with regard to keeping core fluids 40, such as water corefluids, from diffusing out of the liquid core ablation catheter 22during shelf life storage. Packaging the finished and sterilized liquidcore ablation catheter 22 in a high humidity package may mitigate thisproblem in some cases, particularly in instances where FEP is used.Suitable materials for such a package may include an openable enclosuremade from metal coated plastic, PCTFE or any other suitable materialcapable of producing a hermetic or hermetic type seal that is sealableabout a finished ablation catheter or catheter system and is suitablefor a desired type of sterilization such as gamma e-beam or the like.

Other methods for forming such a low index layer from these materialsmay include extruding a thin layer, for example, of solid Teflon AF2400® or Teflon AF 1601®, over a smooth polished metal mandrel to formthe inner luminal layer 48 of the multi-layer catheter tube 38 of theliquid core ablation catheter 22. In some cases, such an extruded thinlayer of low index material may have a thickness of about 5 microns toabout 50 microns. Once the amorphous fluoropolymer inner luminal layer48 is extruded over the mandrel, the outer surface 76 (shown in FIG. 14)of the inner luminal layer 48 may then be etched to promote surfaceadhesion thereto. A thicker wall PCTFE base layer tube 50, or base layertube 50 made from another suitable material, such as FEP, may then beover extruded onto the etched outer surface 76 of the inner luminallayer 48, followed by braiding of a multi-filament braid 52 over theouter surface of the PCTFE tube 50. Then an over-jacket 54 may beextruded over an outer surface of the braided layer 52 and PCTFE basetube 50. For some embodiments, the mandrel may then be removed from themulti-layer catheter tube embodiment 38. The tubular inner lumen 78 thatremains once the mandrel has been removed may then be filled withtransmissive liquid 40 and sealed with optical windows at each end,specifically an input optical window 80 at the proximal end 84 (shown inFIGS. 3 and 6) of the multi-layer catheter tube 38 and an output opticalwindow 82, as shown in FIG. 8, at the distal end 86 (shown in FIG. 3) ofthe multi-layer catheter tube 38. The optical windows 80 and 82 may alsobe transparent to the wavelength of laser energy to be guided therein.

Some methods may include placing multiple coating layers of an amorphousfluorocarbon material dissolved in a solvent over a mandrel wire withheat annealing between layers to above the Tg of the polymer to form theinner luminal layer 48. The outer surface 76 of the inner luminal layer48 may then be etched in order to facilitate adhesion thereto. A PCTFEbase layer tube 50, or base layer tube 50 made from another suitablematerial, may then be over-extruded or otherwise applied over the outersurface 76 of the inner luminal layer 48 with a subsequent braid 52applied to an outer surface of the base layer tube 68 and over jacket 54added to an outer layer of the braid 52 and base layer tube 50 tocomplete the multi-layer catheter tube 38. In this example, all the hightemperature annealing is done with a high temperature mandrel wirebefore the plastics are overlaid. No matter which method is used, thePCTFE base tube 68 is independent of the inner luminal layer 48 whichmay be a thin low IR coating where all the refraction of the guidedlaser energy takes place. In some cases, the thickness of this thininner luminal layer 48 must be at least several wavelengths thick forrefraction as discussed above.

This method may also include coating a mandrel wire with a concentratedsolution of an amorphous fluoropolymer dissolved in a solvent. Thepercentage of solids may be greater than 10% for maximizing wallthickness per coating layer. The coated mandrel wire may then beannealed above the boiling point of the solvent, which may be FC-40whose bp is 155° C. and then annealed up to 30 minutes at or above theglass transition temperature, Tg, of the solid fluoropolymer, which forTelflon AF 1601® may be about 160 degrees C. The thickness of this layermay be about 10 microns to about 50 microns for some embodiments. Thislayer may then etched and over extruded with a water barrier layer suchas PCTFE, braided and then overjacketed.

The input window 80 and output window 82 enclosing the fluid volume 40of the fluid core ablation catheter 22 generally include a material witha high transparency to the ultraviolet high power light pulses from theexcimer laser or other suitable high power laser sources. The inputoptical window 80 as shown in FIG. 6 extends past the interface with themulti-layer catheter tube 38 in order that input laser energy spill overfrom an associated optical coupler 20 does not impinge on themulti-layer catheter tube 38 which could be heated and damaged. Atubular capillary shield 88 (see FIG. 6) may also be placed over theelongated cylindrical window 80 to further shield the catheter tube 38.The input optical window 80 may have a numerical aperture (NA) that isless than or matches the NA of the core fluid 40 of the ablationcatheter 22 for optimum coupling in some cases. For some embodiments,the input optical window 80 may include a silica core silica cladwindow, but it may also include an optically polished silica rod that isradially surrounded by an air interface. The input optical window 80 ofthe ablation catheter 22 may also include a silica rod 90 (see FIG. 10)that has a low index amorphous fluoropolymer coating 91 such as TeflonAF 1601® or similar material applied to an outer surface thereof. Forsome embodiments, the input optical window 80 may have an outer diameteror transverse dimension of about 0.5 mm to about 1.5 mm, morespecifically, about 0.8 mm to about 1.2 mm. The input window 80,capillary shield 88 and proximal end of the ablation catheter 22 areheld in alignment and position for efficient coupling by a coupler body89, as shown in FIG. 6, which includes a barrel member made from a highstrength material with an inner lumen disposed therein. The proximal endof the ablation catheter 22 and distal end of the window 80 abut eachother within the lumen of the barrel of the coupler body 89 as shown inFIG. 7. The capillary shield 88 may extend over the operative junctionbetween the proximal end of the catheter tube 38 and distal end of theinput window 80.

The output optical window 82 as shown in FIG. 10 may have an overalllength selected to minimize stiffness of the distal end 34 of theablation catheter 22. In some cases, the output optical window 82 mayhave a length less than about 10 mm, more specifically, less than about8 mm, even more specifically, less than about 6 mm, to allow the tip tonegotiate curves in the body lumen. This output optical window 82 mayhave a numerical aperture equal to or greater than the numericalaperture of a tubular body portion of the liquid core ablation catheter22 for maximum coupling of laser energy out of the liquid core 40. Thisoutput optical window 82 again may include a high NA optical fiber or asilica rod 90 coated with a low index amorphous fluoropolymer coating91. For some embodiments, the output optical window 82 may have an outerdiameter or transverse dimension of about 0.5 mm to about 1.5 mm, morespecifically, about 0.8 mm to about 1.2 mm.

In order to protect the output optical window 82 from stresses and toease passage of the fluid filled ablation catheter 22, a tapered metalhousing 96 may be used to encapsulate the output optical window 82 asshown in the embodiment of FIG. 10. The output window 82 assembly at thedistal end 34 of the ablation catheter 22 may be arranged with theproximal end 100 of the output optical window 82 extending proximallybeyond a proximal end 98 of the tapered metal housing 96. The proximalend 100 of the output optical window 82 may extend proximally slightlyinto the core liquid 40 of the ablation catheter 22 in some cases asshown in FIG. 10. The tapered metal housing 96 may include an inner borethat extends the length of the tapered metal housing 96 from a proximalend to a distal end thereof. An inside surface 104 of the inner bore maybe sized to fit closely with an outer surface 102 of the coating 91 ofthe output optical window 82 in some cases such that the output opticalwindow 82 is stabilized laterally relative to the tapered housing butwith enough gap to allow materials such as adhesives to extend therein.In some instances, the tapered metal housing 96 may be secured to theoutput optical window 82 by any suitable means such as by crimping,adhesive bonding, brazing, soldering or the like. In some cases, thetapered metal housing 96 may be so secured such that there may be littleto no gap between the inside surface 104 of the inner bore of thetapered metal housing 96 and the outer surface 102 of the coating 91output optical window 82. The tapered metal housing 96 may include atapered distal section 110 that tapers down in outer diameter ordimension from a nominal outer diameter. The tapered distal section 110may taper down to a reduced diameter or transverse dimension that may beup to about 0.012 inches larger than an outer transverse dimension ordiameter of the output optical window 82. In some cases, the tapereddistal section 110 may have a wall thickness at the distal end of thetapered distal section 110 of about 0.003 inches to about 0.005 inches.The tapered metal housing 96 may also include a stepped portion 111 thatextends proximally from a proximal shoulder surface 112 of the tapereddistal section 110. The stepped portion 111 may have a thin walldisposed between the inner bore and an outer surface 108 that has anouter transverse dimension or diameter that is small enough to be pushedinto the inner lumen of the multi-layer catheter tube 38. In some cases,the wall thickness of the stepped portion 111 may be about 0.002 inchesto about 0.006 inches, more specifically, about 0.003 inches to about0.004 inches.

An outer surface 102 of the coating 91 of the output optical window 82may be bonded to the inside surface 104 of the metal housing 96 with anysuitable adhesive 106, such as a medical grade class VI adhesive. Theinside surface 104 of the metal housing 96 may also be secured to theouter surface 102 of the output optical window 82 by any suitable methodincluding crimping, adhesive bonding, soldering, brazing or the likedepending on whether the window 82 is an all glass embodiment or polymercoated embodiment. The outer surface 108 of the stepped portion of themetal housing 96 may be secured to a surface such as an inner luminalsurface 66 of the catheter tube 38 by bonding, such as adhesive bonding,or any other suitable method. The tapered distal section 110 of themetal housing 96 may provide for a more efficient cutting tip during thelaser ablation process in that the configuration may provide for moreactive cutting area relative to the non-cutting area at the distal endof the ablation catheter embodiment 22. In addition, the tapered end 110of the metal housing 96 may facilitate passage of the ablation catheter22 through a lumen created by the laser ablation process. For someembodiments, an outer surface of the tapered end or section 110 may forman angle with respect to a longitudinal axis 109 of the ablationcatheter 22 indicated by arrow 113. The angle 113 of the tapered end 110of the metal housing 96 may be up to about 5 degrees in some cases, morespecifically, about 1 degree to about 2 degrees, for some embodiments.In other embodiments, the angle 113 may be up to about 8 degrees, morespecifically, about 6 degrees to about 8 degrees. Further, the metalhousing 96 may provide mechanical support and strength to the outputoptical window 82 which may be made from brittle or relatively fragilematerials, such as quartz, silica or the like. The tapered metal housing96 may be made from a single piece of high strength metal such asstainless steel, NiTi, titanium or the like. Depending on the metalmaterial of the tapered metal housing 96, the tapered metal housing 96may be visible under fluoroscopic imaging and may be configured to serveas a radiopaque marker for the distal end of the liquid core ablationcatheter 22. Other metals such as gold, tantalum, platinum or the likemay also be included in the tapered metal housing 96 in order tofacilitate radiopacity of the tapered metal housing 96.

Specific examples for use of the liquid core ablation catheter 22 arediscussed herein that are directed to clearing obstructions inperipheral arteries of a patient, but similar approaches may be used forcoronary arteries and other lumens 118 in the human body. To initiate apercutaneous procedure, a short introducing catheter (not shown) may beplaced into an artery of the groin of a patient. All other devices maygenerally be introduced through this introducing catheter, which mayinclude a hemostatic valve to eliminate blood flow out of theintroducing catheter during the procedure. Contrast fluid may beintroduced through this introducer sheath or a longer introducingcatheter may be inserted through the sheath over a guide wire 56, asshown in FIG. 31, to locate this catheter near a target lesion 116disposed within the patient's anatomy.

In some cases, a method embodiment for using a liquid core ablationcatheter system 22 may include placing the low profile support catheter26 through the introducing sheath and advancing the support catheter 26distally into close proximity to a target lesion or material 116 asshown in FIG. 28. In some instances, the support catheter 26 may beadvanced, guided or positioned over a guidewire 56 during this process.If a guidewire 56 is used for advancing the support catheter 26, theguidewire 56 may then be removed once the distal end 120 of the supportcatheter 26 is disposed adjacent a target site or lesion 116. Once theguidewire 56 is removed from the inner lumen 28 of the support catheter26, the liquid core ablation catheter 22 advanced distally within theinner lumen 28 of the support catheter 26 to the target lesion 116 asshown in FIG. 28. Saline may then be flushed through the inner lumen 28of the support catheter 26 and around an outer surface of the liquidcore ablation catheter 22 to remove blood from the tip of the ablationcatheter 22. The laser source 10 may then be energized by depressing thefootswitch 16 and laser energy at a level sufficient to ablate tissuethen be emitted from the distal end 34 of the ablation catheter 22.

Upon activation of the laser, the distal end of the ablation catheter 22may be advanced distally in an axial orientation into the target lesion116 by a distance of about 5 to 10 mm for some embodiments, while thesupport catheter 26 remains substantially stationary with regard to itsaxial position. The support catheter 26 may then be advanced distallyover the ablation catheter 22 and through the lumen 122 created by theactive ablation catheter 22 until the distal tip 120, as shown in FIG.4, of the support catheter 26 is substantially even with the distal tip34 of the ablation catheter 22 as shown in FIG. 29. The relativepositions of the respective distal ends 120 and 34 of the supportcatheter 26 and ablation catheter 22 may be determined by fluoroscopicimaging of the respective radiopaque marker bands 31 at the respectivedistal ends 120 and 34. The process is repeated as shown in FIG. 30until the ablation catheter 22 crosses the lesion 116 as shown in FIG.31. The ablation catheter 22 is removed with the support catheter 26left in place and a guidewire 56 is advanced though the newly createdchannel or lumen 122. The support catheter 26 may then be retracted asshown in FIG. 32. Other devices, such as a balloon or a stent, may thenbe deployed over this guidewire 56 to achieve the necessary openingdiameter in the vessel for adequate blood flow. If the laser catheter 22produces a sufficient lumen 122, then no further treatment withadditional devices is required in some instances.

For such a procedure, the support catheter 26 may be configured to havea low profile with thin walls to be able to follow the ablation catheter22 through the lesion 116 and maintain the ablation end parallel to thelumen 122 to prevent perforation. To achieve this, the support catheter26 may be a multilayer design with a thin wall liner 124 of a lowfriction Teflon®, such as polytetrafluoroethylene (PTFE) to allowpassage of the ablation catheter with ease. An embodiment of thestructure of a suitable support catheter is shown in FIG. 18.

Referring to FIG. 18, this liner 124 of the support catheter 26 may havean over layer or base layer tube 126 then a metal braid layer 128disposed or braided over the base layer tube 126 to achieve pushabilityand kink resistance and torque. The base layer disposed over the PTFEliner 124 may have a high durometer with a very thin coating and anideal material may include a polyimide base layer tube 126 covered witha thin over-jacket 130 of a lower durometer material for flexibilityover the braid material layer 128. A wall thickness of the supportcatheter 26 of less than about 0.005″ may be used for low profile forpassage of the support catheter 26 through the opening or lumen 122 madeby the liquid core ablation catheter 22. In essence this method mayproduce a result which is equivalent to a result achieved by using anexternal guidewire 56 for location of a cutting tip of an over-the-wiretype design of the ablation catheter 22 as shown in FIGS. 15 and 16. Theinner lumen 28 of the support catheter 26 may also include sufficientspace or cross sectional area to accommodate both the ablation catheter22 and a lumen or longitudinal space therebetween for flow of saline. Aflow of saline or other desired fluid between an outside surface of theliquid core ablation catheter 22 and an inside surface of the innerlumen 28 of the support catheter 26 may be used to clear the blood whichis disposed at the target lesion 116 site. In some cases, the saline maybe introduced into the inner lumen 28 of the support catheter 26 with asyringe 19, as shown in FIG. 1, coupled to the Y connector 32 of thecatheter system 27 as shown in FIGS. 1 and 2.

Some support catheter embodiments 26 may be straight as shown in FIG. 19or have an angled tip as shown in the support catheter embodiment ofFIG. 21 depending on the vessel contour at the lesion site. The supportcatheter 26 may have a low friction lubricious outer coating 132 on anouter surface 134 thereof (as shown in FIG. 18) for low friction passagethough tissue follow the ablation catheter 22 through the lumen 122created by the ablation catheter 22 through the target lesion 116.Visualization of the location of both the support catheter 26 and theablation catheter 22 in the vessel lumen 118 and with respect to eachother may be made by means of one or more radiopaque markers 31 or 136disposed on the respective catheters at desired locations and with aleast one marker located at each distal tip (120 and 34 respectively) ofthe catheters.

Interventional physicians often rely on a guidewire 56 for advancingmultiple devices to treat a lesion 116 within a patient's vasculatureand to maintain the position of a catheter inside the lumen walls. Somemethod embodiments discussed herein may include the use of a guidewire56 to advance and/or position the support catheter 26. Once the supportcatheter 26 is properly positioned at a desired site within thepatient's body, the guidewire 56 may then be removed and replaced withan ablation catheter such as the liquid core ablation catheter 22. Someinterventionalist's may prefer the protection of a guidewire 56 to placeother devices over in case of adverse event. In such cases, the ablationcatheter 22 may be removed and a guidewire 56 inserted through the innerlumen 28 of the support catheter 26 and other treatment devices may thenbe passed over the guidewire 56 through the inner lumen 28 of thesupport catheter 26. In addition, the support catheter 26 may be removedbefore inserting other devices in some cases. One or more separateguidewire lumens 60 and 62 may also be attached to or integral with thesupport catheter 26 as shown on the support catheter embodiment 26′″ ofFIGS. 26 and 27. Additionally, a guidewire lumen may be added to theablation catheter 22′ as shown in FIGS. 15 and 16. In some cases, aseparate guidewire lumen 60 or any of the guidewire lumens discussedherein may be suitable for passage of a 0.014″ sized guidewire or thelike may be used for additional protection. In some cases, thisguidewire lumen would only have a short length at the distal end for arapid exchange type configuration. This configuration could apply to theboth the ablation catheter 22′ and the support catheter 26″. That waythe physician would always have a guidewire present in case of anadverse event and has the ability to withdraw the liquid core ablationcatheter 22 and advance a guidewire 56 over a total occlusion after thedense cap entrance to the total occlusion is cleared by energy emittedfrom the liquid core laser ablation catheter 22 as shown in FIG. 32. Forsome embodiments, the guidewire lumens 60 and 62 may have a length of atleast about 10 cm. In addition, the respective distal ports of theguidewire lumens 60 and 62, which may be disposed along an outer surfaceof support catheter embodiments 26′″, may be disposed proximally from adistal end of the support catheter 26′″ by at least about 5 mm.

For some embodiments, a support catheter such as the support catheter26′″ may have multiple guidewire lumens 60 and 62 as shown in theembodiment of FIGS. 26 and 27, a support catheter such as the supportcatheter 26″ may have a tapered distal section as shown in theembodiment of FIG. 20, and the support catheter 26′ may have a bend atthe end as shown in the support catheter embodiment of FIG. 21 tonegotiate bends in the artery or to displace the ablation catheter 22towards an eccentric plaque. The multiple guidewire lumens 60 and 62 maybe used for saline flush, contrast injection or for passage of aguidewire 56 in some cases.

For some indications, it may be desirable to make a channel in apatient's vessel lumen that is larger in transverse dimension than atransverse dimension of the ablation catheter 22 itself. For some suchcases, after the liquid core ablation catheter 22, or any other suitableablation catheter embodiment discussed herein, forms an initial channeland opens an occlusion 116 in a patient's vessel 118, a guidewire 56 orother device may then be inserted in the opening or newly formed channel122. The ablation catheter 22 may then be activated to emit ablationenergy and advanced through the initial channel 122 adjacent thesubstantially parallel guidewire 56 to produce a lumen 122′ which islarger than the lumen made with the first active pass of the ablationcatheter 22. Such a technique embodiment is shown in FIGS. 33-35.Embodiments of this procedure may be completed with a second guidewire56′ in a second guidewire lumen 60 or 62 of a support catheterembodiment 26′″ and a final pass made. This method may produce a lumen122′ having a larger inner transverse dimension or diameter andcorresponding larger transverse cross section than an outer transversedimension or diameter or cross section of the ablation catheter 22 usedto make the initial channel 122. During this type of method embodiment,the guidewire placements after the first or initial lumen is made blockpart of the initially created lumen which laterally forces the distalend of the liquid core ablation catheter 22 up against the remainingplaque 116. Such partial filling the first or initial channel with one,two, three or more guidewires 56 and 56′ forces the ablation catheter 22to ablate tissue disposed laterally with respect to the initial channel122 formed by the ablation catheter 22. Without the guidewire placementin the initial channel 122, the ablation catheter 22 would likely justgo through the first or initial lumen 122 on a second pass with nofurther ablation or channel widening or increase in cross sectionalarea. Such an increase in cross sectional area of the ablation channelallows more blood or other fluid to flow therethrough for a fixedpressure.

Referring to FIGS. 37-42, a variety of manufacturing steps are shownwhich may be useful for some or all of the processing method embodimentsdiscussed above. In particular, FIG. 37 illustrates a polished metalmandrel 140 being passed through an extruder device 142 and applying alayer of amorphous fluoropolymer 144 to an outer surface of the mandrel140. FIG. 38 shows a mandrel 140 having a solution of amorphousfluoropolymer 145 being applied to an outside surface of the mandrel 140by a spray coating device 146 to produce a thin layer of amorphousfluoropolymer 144. FIG. 39 depicts a mandrel 140 with a coating ofamorphous fluoropolymer solution 145 disposed in an oven 148 for thermalprocessing to drive off the solvent of the fluoropolymer solution 145.FIG. 40 shows a mandrel 140 with a layer of amorphous fluoropolymer 144applied thereto being passed through an extruder 142 to apply a layer ofbase tube material 150. FIG. 41 shows the mandrel 140 of FIG. 40 with alayer of amorphous fluoropolymer 144 and subsequent base layer tubematerial 150 being passed through a braiding device 152 to apply abraided layer 154 to the base tube layer 150. FIG. 42 shows the mandrel140 and layers 144, 150 and 154 being passed through an extruder 142 toapply an outer jacket layer 156. FIG. 43 shows an amorphousfluoropolymer solution 145 being injected into a catheter tube 38 by apressurized amorphous solution source 158 which may be further processedto remove the solvent from the solution 145 in an oven 148 as shown inFIG. 39.

FIG. 44 shows a distal portion of an embodiment of a liquid coreablation catheter that may have some or all of the properties of liquidcore ablation catheter 22 discussed above. Once again, in order toprotect the output optical window 82 from stresses and to ease passageof the fluid filled ablation catheter 22 through tissue during ablation,a tapered metal housing 196 may be used to encapsulate the outputoptical window 82 as shown in the embodiment of FIG. 44. The outputwindow 82 assembly at the distal end 34 of the ablation catheter 22 maybe arranged with the proximal end 100 of the output optical window 82extending proximally beyond a proximal end 198 of the tapered metalhousing 196.

The proximal end 100 of the output optical window 82 may extendproximally slightly into the core liquid 40 of the ablation catheter 22in some cases as shown in FIG. 44. The tapered metal housing 196 mayinclude an inner bore 197 that extends the length of the tapered metalhousing 196 in a proximal direction from a distal end 199 of the housing196 to a distal end 200 of a stepped portion 202 of the housing 196. Aninside surface 204 of the inner bore may be sized to fit closely with anouter surface 102 of the coating 91 of the output optical window 82 insome cases such that the output optical window 82 is stabilizedlaterally relative to the tapered housing but with enough gap to allowmaterials such as adhesives to extend therein. In some instances, thetapered metal housing 196 may be secured to the output optical window 82by methods such as by crimping, adhesive bonding, soldering, brazing orthe like. In some cases the tapered metal housing 196 may be securedsuch that there may be little to no gap between the inside surface 204of the bore 197 of the tapered metal housing 196 and the outer surface102 of the coating 91 of the output optical window 82. The tapered metalhousing 196 may include a tapered distal section 110 that tapers down inouter diameter or dimension from a nominal outer diameter. The tapereddistal section 110 may taper down to a reduced diameter or transversedimension that may be up to about 0.012 inches larger than an outertransverse dimension or diameter of the output optical window 82, insome cases up to about 0.010 inches larger. In some cases, the tapereddistal section 110 may have a wall thickness at the distal end 199 ofthe tapered distal section 110 of about 0.003 inches to about 0.005inches. The stepped portion 202 of the housing 196 may have a thin walldisposed over a reduced diameter portion 206 of a distal section of themultilayer catheter tube 38. In some cases, the stepped portion 202 ofthe tapered metal housing 196 may have the same or similar longitudinallength as that of the reduced diameter portion 206 of the distal sectionof the multilayer catheter tube 38. In some cases, the wall thickness ofthe stepped portion 202 may be about 0.002 inches to about 0.005 inches,more specifically, about 0.003 inches to about 0.004 inches. In somecases, the wall thickness of the reduced diameter portion 206 of themultilayer catheter tube 38 may be sized to have an overall outerdiameter to substantially match an inside diameter or transversedimension of the stepped portion 202 of the tapered metal housing 196.In addition, the inside surface of the stepped portion 202 may besecured to an outer surface of the reduced diameter portion 206 with anadhesive bond, crimp connection or the like. In some instances, it maybe desirable for an outside diameter or transverse dimension of thetapered metal housing 196 to be the same as or substantially the same asan outside diameter or transverse dimension of the nominal multilumencatheter tube 38 so as to provide a smooth regular transition between anoutside surface of the tapered metal housing 196 and an outside surfaceof the multilumen catheter tubing 38.

The outer surface 102 of the output optical window 82 may be bonded toan inside surface 204 of the metal housing 196 with any suitableadhesive 106, such as a medical grade class VI adhesive or the like. Forall glass embodiments of the output optical window 82, methods such assoldering or bronzing may be used. The inside surface 204 of the bore197 of the metal housing 196 may also be mechanically secured to theouter surface 102 of the output optical window 82 by methods such ascrimping or any other suitable mechanical method as discussed herein. Asdiscussed above, the tapered distal section 110 of the metal housing 196may provide for a more efficient cutting tip during the laser ablationprocess in that the configuration may provide for more active cuttingarea relative to the non-cutting area at the distal end of the ablationcatheter embodiment 22. In addition, the tapered end 110 of the metalhousing 196 may facilitate passage of the ablation catheter 22 through alumen created by the laser ablation process. For some embodiments, thetapered end 110 of the tapered metal housing 196 may have the same orsimilar configuration as that of tapered metal housing 96 discussedabove and as shown in FIGS. 10-12. In particular, the tapered end 110may form an angle 113 with respect to a longitudinal axis 109 of theablation catheter 22 indicated by arrow 113 in FIG. 10 of up to about 5degrees in some cases, more specifically, about 1 degree to about 2degrees, for some embodiments. In some instances, the tapered end 110 ofthe tapered metal housing 96, or any other tapered metal housingembodiment discussed herein, may form an angle 113 of up to about 9degrees, more specifically, of about 6 degrees to about 8 degrees.Further, the metal housing 196 may provide mechanical support andstrength to the output optical window 82 which may be made from brittleor relatively fragile materials, such as quartz, silica or the like. Thetapered metal housing 196 may be made from a single piece of highstrength metal such as stainless steel, titanium or the like. Dependingon the metal material of the tapered metal housing 196, the taperedmetal housing 196 may be visible under fluoroscopic imaging and may beconfigured to serve as a radiopaque marker for the distal end of theliquid core ablation catheter 22. Other metals such as gold, tantalum,platinum or the like may also be included in the tapered metal housing196 in order to facilitate radiopacity of the tapered metal housing 196.

FIGS. 46-50 illustrate an embodiment of a high energy laser coupler 220that may be operatively coupled to a proximal end of any of the liquidcore ablation catheters embodiments 22 discussed herein as well as anyother suitable laser ablation catheter. For some embodiments, the highenergy laser coupler 220 may include a coupler body 222 that has aproximal section 224 with a cylindrical outer surface 226 and an innerbore 228 which is disposed concentrically within the cylindrical outersurface 226. The inner bore 228 extends distally from a proximal end 230of the coupler body 222 to a proximal end 232 of a window connector bore234. The window connector bore 234 is disposed at a distal end of theinner bore 228. The coupler body 222 also includes a distal section 236extending distally from the window connector bore 234.

A window connector body 240 includes a proximal section 241 with acylindrical outer surface which may be configured to fit closely withinan inside surface of the window connector bore 234 of the coupler body222. A flange portion 244 of the window connector body 240 is disposedat a distal portion or distal end of the proximal section 241 andextends radially outward from a nominal outer surface 246 of theproximal section 241 of the window connector body 240. The windowconnector body 240 also includes a stepped portion 250 which extendsdistally from the proximal portion and has an outer diameter ortransverse dimension that is less than an outer diameter or transversedimension of the proximal section 241 of the window connector body 240.The outer diameter of the stepped portion 250 may be configured toextend within an inner lumen of a proximal section of the multilayercatheter tube 38. An outer surface 252 of the stepped portion 250 may besecured to an inside surface of the proximal section of the multilayercatheter tube 38 by an adhesive bond, crimp bond or the like. An innerbore 254 extends the length of the window connector body 240 from aproximal end 242 to a distal end 245 thereof. The inner bore 254 may bea straight bore that is configured to fit closely with an outer surface256 of an optical input window 80 disposed within and secured to theinner bore 254 of the window connector body 240. The outer surface 256of the optical input window 80 may be secured to an inside surface ofthe inner bore 254 of the window connector body 240 with an adhesivebond, crimp bond, solder bond, braze bond or the like. In some cases, itmay be desirable for the bond between the outer surface 256 of the inputoptical window 80 and the inside surface of the bore 254 of the windowconnector body 240 to be fluid tight.

In some instances, a proximal end of the optical input window 80 mayextend proximally from a proximal end 242 of the proximal section 241 ofthe window connector body 240. As shown in FIGS. 49 and 50, a proximalportion of the flexible waveguide catheter tube 38 is disposed over thestepped portion 250 of the window connector body 240 with a cylindricalmetal sleeve 260 disposed over the proximal portion of the flexiblewaveguide catheter tube 38. The cylindrical metal sleeve 260 may bedisposed so at to secure an inside surface of the catheter tube 38 to anoutside surface of the stepped portion 250 of the window connector body240 in a fluid tight seal. The inside surface of the multilayer cathetertube 38 may be secured to an outside surface of the stepped portion 250with an adhesive bond 263. In some cases, an inside surface 262 of themetal sleeve 260 may be secured to an outside surface of a proximalportion 267 of the multilayer catheter tube 38 with an adhesive bond263, with a crimp body or the like. In addition, a potting material 264such as an adhesive or the like may be used to provide mechanicalsupport and strain relief between an outer surface of the multilayercatheter tube 38 and an inside surface of a back bore 266 of the distalsection of the coupler body 222.

The optical input window 80, which may include a multi-mode length ofoptical fiber in some instances. In some embodiments, the optical inputwindow 80 may extend distally of a distal end 245 of the stepped portionof the window connector body 240 making direct contact with liquid corefluid 40 of the liquid core ablation catheter. In some instances, theoptical input window may have axial length of about 0.5 inches to about1 inch. For some embodiments, the stepped portion of the windowconnector body may have a wall thickness of about 0.002 inches to about0.004 inches.

Regard packaging and transportation of liquid core ablation catheterembodiments discussed herein, certain conditions or structures may bedesirable in order to keep the catheter embodiments in good workingorder. In some cases, it may be important to maintain a minimum vaporpressure of liquid in the environment surrounding some liquid coreablation catheter embodiments 22 in order to prevent loss of core fluid40 during storage or transportation of the catheter 22 due to diffusionthrough the catheter tube 38. It may also be important to minimizetemperature extremes to which some liquid core ablation catheterembodiments are exposed. FIG. 51 shows a liquid core ablation catheterpackage assembly 250 that includes a thin walled hermetically sealedenclosure 252 including an interior volume 254. In some cases, amaterial of the enclosure 252 may be suitable for gamma sterilization. Aliquid core ablation catheter 22 is shown disposed within the interiorvolume 254 of the hermetically sealed enclosure 252, however, anysuitable liquid core ablation catheter discussed herein may be sopackaged. A liquid 256 is disposed within the interior volume and isconfigured to maintain a vapor pressure within the interior volume 254sufficient to prevent loss of a liquid 40 of a liquid core 40 of theliquid core ablation catheter 22 due to diffusion of the liquid core 40into the interior volume 254. The hermetic properties of the enclosure252 prevents the liquid 256 from escaping the enclosure 252, thus only asmall amount of the liquid 256 may be necessary. In some instances, thethin walled hermetically sealed enclosure may be made from a thinmetalized plastic or a non-metalized thin plastic such as PCTFE thatfunctions as a suitable liquid vapor barrier. The thin walled plasticmay include heat sealed edges in order to form the enclosure from twoflat thin sheets of the plastic material. The package assembly may alsoinclude a liquid depot 258 that contains the liquid 256 disposed withinthe interior volume 254. In some cases, the liquid depot 258 may includea sponge or the like that may also be configured to absorb a liquid suchas the core liquid 40 and be suitable for gamma sterilization. Inaddition, the sealed enclosure 252 may be disposed within asubstantially rigid box 260.

With regard to the above detailed description, like reference numeralsused therein may refer to like elements that may have the same orsimilar dimensions, materials and configurations. While particular formsof embodiments have been illustrated and described, it will be apparentthat various modifications can be made without departing from the spiritand scope of the embodiments of the invention. Accordingly, it is notintended that the invention be limited by the forgoing detaileddescription.

The entirety of each patent, patent application, publication anddocument referenced herein is hereby incorporated by reference. Citationof the above patents, patent applications, publications and documents isnot an admission that any of the foregoing is pertinent prior art, nordoes it constitute any admission as to the contents or date of thesedocuments.

Modifications may be made to the foregoing embodiments without departingfrom the basic aspects of the technology. Although the technology mayhave been described in substantial detail with reference to one or morespecific embodiments, changes may be made to the embodimentsspecifically disclosed in this application, yet these modifications andimprovements are within the scope and spirit of the technology. Thetechnology illustratively described herein suitably may be practiced inthe absence of any element(s) not specifically disclosed herein. Thus,for example, in each instance herein any of the terms “comprising,”“consisting essentially of,” and “consisting of” may be replaced witheither of the other two terms. The terms and expressions which have beenemployed are used as terms of description and not of limitation, and useof such terms and expressions do not exclude any equivalents of thefeatures shown and described or portions thereof, and variousmodifications are possible within the scope of the technology claimed.The term “a” or “an” may refer to one of or a plurality of the elementsit modifies (e.g., “a reagent” can mean one or more reagents) unless itis contextually clear either one of the elements or more than one of theelements is described. Although the present technology has beenspecifically disclosed by representative embodiments and optionalfeatures, modification and variation of the concepts herein disclosedmay be made, and such modifications and variations may be consideredwithin the scope of this technology.

Certain embodiments of the technology are set forth in the claim(s) thatfollow(s).

What is claimed is:
 1. A support catheter for use supporting a liquidcore ablation catheter, comprising: a thin inner tubular layer thatcomprises an inner lumen with an inner diameter which is configured toaccommodate passage of a liquid core ablation catheter and spacetherebetween sufficient for saline injection to flush blood and contrastfluid in front of the liquid core ablation catheter distal end and thatcomprises a low friction material to ease passage of the ablationcatheter; an over layer of high durometer material disposed over thethin inner tubular layer; a braided layer disposed over an outer surfaceof the over layer; an outer layer covering the braided layer; a wallthickness of less than about 0.006 inches; a second lumen configured fora passage of a guide wire that is disposed on an outer surface of thesupport catheter, includes a length of at least about 10 cm and includesa distal port disposed proximally of a distal end of the supportcatheter; and wherein the support catheter has the required torque,pushability and kink resistance to guide the liquid core ablationcatheter with a low enough profile to advance through an openinggenerated by laser ablation of tissue with the liquid core ablationcatheter.
 2. The support catheter of claim 1 wherein the low frictionmaterial comprises PTFE, a hybrid of PTFE or other low friction polymersuitable for sterilization.
 3. The support catheter of claim 1 furthercomprising at least one radiopaque marker disposed near the distal endto visualize the position of the distal end in a patient's lumen and aposition of the support catheter with respect to an ablation catheterdisposed within the support catheter.
 4. The support catheter of claim 1wherein a distal section of the support catheter comprises asubstantially straight longitudinal section.
 5. The support catheter ofclaim 1 further comprising an angled distal section configured forproper positioning of a distal end of an ablation catheter disposedwithin the support catheter.
 6. The support catheter of claim 1 furthercomprising an angled distal section configured to nutate a distal end ofan ablation catheter disposed within and extending distally from thesupport catheter upon rotation of the support catheter about alongitudinal axis thereof.
 7. The support catheter of claim 6 whereinthe angled distal section has a length of about 5 mm to about 50 mm. 8.The support catheter of claim 6 wherein a discharge axis of the angleddistal section forms an angle of about 3 degrees to about 10 degreeswith respect to a longitudinal axis of the support catheter.
 9. Thesupport catheter of claim 1 wherein a distal section of the supportcatheter comprises a tapered distal section configured to align a distalend of an ablation catheter which is disposed within the supportcatheter away from a lumen wall.
 10. A multi-lumen support catheter,comprising at least two guidewire lumens and a working lumen configuredfor passage of an ablation catheter.
 11. The support catheter of claim10 wherein a distal port of each respective guidewire lumen is disposedproximally from a distal tip of the support catheter.
 12. The supportcatheter of claim 10 wherein one or more of the guide wire lumensinclude a length of at least about 10 cm.
 13. A method of ablation ofblockages in a lumen of a human vessel, comprising: positioning asupport catheter at a target site of a blockage of the vessel; insertinga liquid core ablation catheter adjacent the blockage; injecting salinethrough an inner lumen of the support catheter to flush contrast fluidand blood from a distal tip of the liquid core ablation catheter;advancing the liquid core ablation catheter while lasing and emittingablation energy from a distal end of the liquid core ablation catheterup to about 5 mm from a distal end of the support catheter; andrepositioning the support catheter and continuing this process until theblockage is traversed.
 14. The method of claim 13 wherein at least oneradiopaque marker is disposed on each catheter and wherein theradiopaque markers are used to identify a location of each catheter inthe lesion and the location of each catheter with respect to each otherduring the lasing.
 15. The method of claim 13 further comprisingenlarging a lumen produced by traversing the blockage, comprising: usinga support catheter comprising at least one guidewire lumen separate fromthe inner lumen to pass one or more guide wires into the open lumen withthe liquid core ablation catheter withdrawn from the lumen to fill thelumen opening; and advancing the liquid core ablation catheter throughthe lumen.
 16. A high energy laser coupler, comprising: a coupler bodyincluding a proximal section with a cylindrical outer surface, an innerbore disposed concentrically within the cylindrical outer surface andextending distally from a proximal end of the coupler body, a windowconnector bore disposed at a distal end of the inner bore, and a distalsection extending distally from the window connector bore; a windowconnector body having a proximal section with a cylindrical outersurface configured to fit closely with an inside surface of the windowconnector bore of the coupler body, a flange portion disposed at adistal end of the proximal section, a stepped portion extending distallyof the flange portion and an inner bore extending the length of thewindow connector body from a proximal end to a distal end thereof; anoptical input window disposed within and secured to the inner bore ofthe window connector body such that a proximal end of the optical inputwindow extends proximally from a proximal end of the proximal section ofthe window connector body; a flexible waveguide catheter tube includinga proximal portion thereof disposed over the stepped portion of thewindow connector body; and a cylindrical metal sleeve disposed over theproximal portion of the flexible waveguide catheter tube so at to securethe catheter tube to the stepped portion of the window connector body.17. The high energy laser coupler of claim 16 wherein the optical inputwindow comprises a multi-mode length of optical fiber.
 18. The highenergy laser coupler of claim 16 wherein the metal sleeve is secured tothe proximal end of the catheter tube by adhesive bonding.
 19. The highenergy laser coupler of claim 16 wherein the metal sleeve is crimped tothe outer surface of the proximal end of the catheter tubing.
 20. Thehigh energy laser coupler of claim 16 wherein the optical input windowhas an axial length of about 0.5 inches about 1 inch.
 21. The highenergy laser coupler of claim 16 wherein the stepped portion has a wallthickness of about 0.002 inches to about 0.005 inches.
 22. The highenergy laser coupler of claim 16 wherein the optical input windowextends distally of a distal end of the stepped portion of the windowconnector body making direct contact with liquid core fluid of theliquid core ablation catheter.
 23. An ablation catheter, comprising: anelongate catheter body; a transmissive core which is configured totransmit high energy laser light and which extends longitudinally from aproximal end to a distal end of the elongate catheter body; an inputsurface in optical communication with the transmissive core at aproximal end of the elongate catheter body; an output surface in opticalcommunication with the transmissive core at a distal end of the elongatecatheter body; and a tapered housing which includes a distal end havingan inner bore that is disposed about the output surface, which includesa distal end that is longitudinally coextensive with a distal end of theoutput surface, which includes a tapered distal section that terminatesdistally with a thin wall that facilitates passage of a distal end ofthe ablation catheter through a lumen within a patient's body and whichis configured to be sufficiently radiopaque in such as to be viewable byfluoroscopic imaging during a medical procedure.
 24. The ablationcatheter of claim 23 wherein the tapered housing comprises a taperedmetal housing.
 25. The ablation catheter of claim 24 wherein the taperedmetal housing further comprises a stepped portion at a proximal sectionthereof which is configured to couple to a corresponding stepped portionof a catheter tube of the elongate catheter body so as to provide asmooth transition between an outer surface of the tapered metal housingand an outer surface of the catheter tube.